Abscess - a hole filled with pus that forms as a result of a local infection.

Adenocarcinoma - cancerous tumors of the glands, such as in the ducts or lobules of the breast.

Adenoma - benign growths that often appear on glands or in glandular tissue.

Adjuvant therapy - radiation therapy, chemotherapy, or hormone therapy given in addition to surgery for the removal of cancer as a safety factor to kill any cancer cells that cannot be seen.

Adrenal gland - two small glands located on top of the kidneys that secrete hormones.

Advanced cancer - stage of cancer in which the disease has spread from the primary site to other parts of the body.

Allogeneic transplant - the transfer of bone marrow or peripheral stem cells from one person to another.

Alopecia - a partial or complete loss of hair that may result from radiation therapy to the head, chemotherapy, skin disease, drug therapy, and natural causes.

American Cancer Society - an organization that supports research, offers educational materials and programs, and offers many other services to cancer patients and their families.

Androgen - male sex hormone that may be used to treat recurrent breast cancer by opposing the activity of estrogen.

Anesthesia - lack of normal sensation, especially the awareness of pain, which may be brought on by anesthetic drugs. General anesthesia causes loss of consciousness; local or regional anesthesia causes loss of feeling only to a specified area.

Antibiotic - chemical substances that are either produced from cultures of microorganisms or produced artificially for the purpose of killing other organisms that cause disease. Antibiotics may be needed along with cancer treatment to prevent or treat infections.

Antibody - a protein (made by white blood cells) that defends against invading foreign agents, such as bacteria, as part of the immune system response.

Breast conservation therapy - surgery to remove a breast cancer and a small amount of benign tissue around the cancer without removing any other part of the breast. These procedures include a lumpectomy or a partial (segmental) mastectomy.

Breast implant - a manufactured flexible sac that is filled with sterile saline or silicone gel that is used for either breast augmentation or reconstruction.

Breast reconstruction - surgery to rebuild a breast mound after a mastectomy.

Breast self-examination (BSE) - a method in which a woman examines her breasts and the surrounding areas for lumps or changes. A BSE can be performed once a month, usually at a time other than the days before, during, or immediately after the menstrual period.

Breast specialist - term describing healthcare professionals who have a dedicated interest in breast health.

Diagnostic mammogram - an X-ray of the breast used to diagnose unusual breast changes, such as a lump, pain, nipple thickening or discharge, or a change in breast size or shape. A diagnostic mammogram is also used to evaluate abnormalities detected on a screening mammogram.

Ducts - narrow tube structures or channels that carry body fluids. In the breast, ducts transport milk from the lobules to the nipple.

Fat necrosis - a benign breast condition in which painless, round, firm lumps caused by damaged and disintegrating fatty tissues form in the breast tissue, often in response to a bruise or blow to the breast.

Fibroadenoma - a solid, smooth, benign lump that is commonly found in women in their late teens and early 20s.

Lobe - a roundish projection of any structure. In the breast, lobes of the mammary glands radiate from the central area to the nipple area like wheel spokes.

Lobule - a subdivision of a lobe in the breast.

Lumpectomy - surgery to remove the cancerous lump and a portion of normal tissue around the breast cancer lump.

Lymph - a clear, colorless fluid containing water and a few blood cells that circulates through the lymphatic system and is filtered by the lymph nodes.

Lymph nodes - small bean-shaped structures that help to filter excess fluid, bacteria, and by-products of infections. Most lymph nodes are clustered in specific areas of the body, such as the neck, lower arm, armpit, and groin.

Lymphatic system - a complex network of capillaries, thin vessels, valves, ducts, nodes, and organs that helps to protect and maintain the fluid environment of the body by filtering and draining lymph.

Lymphedema - a disorder in which lymph builds up in the soft tissues, resulting in swelling. Lymphedema may be caused by inflammation, obstruction, or removal of the lymph nodes during surgery.

Mastalgia - pain in the breast that is generally classified as either cyclical (associated with menstrual periods) or noncyclical.

Mastectomy - surgery to remove portions or all of the breast.

Mastitis - an inflammation of the breast tissue.

Metastasize - when cancer cells spread to other parts of the body.

Modified radical mastectomy - the removal of the entire breast (including the nipple, the areola, and the overlying skin), some of the lymph nodes under the arm (also called the axillary lymph glands), and the lining over the chest muscles. In some cases, part of the chest wall muscles is also removed.

Partial (segmental) mastectomy - surgery to remove the breast cancer and a larger portion of the normal breast tissue around the breast cancer, but not the entire breast. The surgeon may also remove the lining over the chest muscles below the tumor and some of the lymph nodes under the arm.

Radical mastectomy - surgery to remove the entire breast (including the nipple, the areola, and the overlying skin), the lymph nodes under the arm, also called the axillary lymph glands, and the chest muscles.

Tamoxifen - a drug used in hormone therapy to treat breast cancer by blocking the effects of estrogen.

Total (or simple) mastectomy - surgery to remove the entire breast (including the nipple, the areola, and most of the overlying skin) and may also remove some of the lymph nodes under the arm, also called the axillary lymph glands.